1. Field of the Invention
The present invention relates to an oil cooler configured to cool oil that circulates within an engine, and a small watercraft comprising the oil cooler.
2. Description of the Related Art
In recent years, jet-propulsion personal watercraft, which are one type of small watercraft, have been widely used in leisure, sport, rescue activities, and the like. The personal watercraft is equipped with an engine within a space surrounded by a hull and a deck. The personal watercraft is configured to have a water jet pump that pressurizes and accelerates water sucked from a water intake generally provided on a hull bottom surface and ejects it rearward from an outlet port. As the resulting reaction, the personal watercraft is propelled forward.
Oil circulates within the engine mounted in the personal watercraft to lubricate and cool various components within the engine. In order for the oil to fully function, the oil is required to have a proper temperature. However, the oil that has circulated within the engine has a relatively high temperature, and therefore, an oil cooler is used to cool the oil (see Japanese Issued Patent No. 3276593, FIG. 2). In some cases, conventional oil coolers are positioned distant from the engine (mainly comprised of a crankcase, a cylinder block, and a cylinder head), for example, in the vicinity of an oil tank provided to be independent of the engine.
A number of pipes, for example, a pipe that draws the oil into the oil cooler, a pipe that draws the oil out of the oil cooler, a pipe that draws a coolant to the oil cooler, and a pipe that discharges the coolant from the oil cooler, are connected to the oil cooler. For maintenance of the oil cooler, it is necessary to attach and detach these pipes to and from the oil cooler, which is burdensome. In addition, these pipes may have a complex piping configuration. Since the piping configuration is complex and the oil cooler is positioned distant from the engine, the lengths of the pipes are extended, which makes it difficult to achieve a lightweight small watercraft.
Another prior oil cooler is made of steel plate and mounts directly on an outer wall face of a crankcase. However, such an oil cooler has difficulty in removing unwanted substances from a coolant passage, and hence is not suitable for use in an engine having an open-looped cooling system in which water is drawn from outside for use as cooling water.